Safety device for motion-picture-projecting machines.



N. POWER.

SAFETY DEVICE FOR MOTION PICTURE PROJECTING MACHINES.

APPLICATION FILED JAN 6.1913.

1 1 9 1,224. Patented July 18, 1916.

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APPLICATION FILED JAN. 5. 1913.

Patented July 18, 1916.

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NICHOLAS POWER, OF BROOKLYN, NEW YORK, ASSIGNOR TO NICHOLAS POWERCOMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

SAFETY DEVICE FOR MOTION-PICTURE-PROJECTING MACHINES.

Specification of Letters Patent.

Patented July 18, 1916.

7 To all whom it may concern:

Be it known that I, NICHOLAS POWER, a citizen of the United States,residing in Brooklyn, county of Kings, and State of New York, (whosepost-ofiice address is No. 388 Jefferson avenue,) have invented new anduseful Improvements in Safety Devices for Motion-Picture-ProjectingMachines, of which the following is a specification.

This invention relates to safety devices for motion picture projectingmachines, and particularly to mechanism for eliminating the chief causesof the film catching fire.

In motion picture projecting machines, as now almost universallyconstructed, the essential elements consist of a lamp and lenses forprojecting the picture, a frame having an aperture corresponding in sizewith the individual pictures on the film strip, a shutter forperiodically cutting off the light between the. lens andthe screen, anda feed mechanism acting during such period to intermittently feed thesuccessive pictures into registration with the projection aperture.

' the .p videam p ing breaking of the film, the failure .of the feedmechanism, or fromanyother cause of ,the films" remaining stationa-ry.for an ab The lamps employed in' such apparatus are usually powerful arclamps or other intense lights, sufficient when concentrated upon thesame portion of the film for any appreciable time to cause the same toignite and perhaps cause a serious accident, for even though the firemay be extinguished before material damage is done, the smell of theburning film in the theater and the momentary projection on the screenof the image of the fire not infrequently causes a panic among thespectators. To prevent such ignition when the machine is not inoperation, most machines are provided with a door or fire shield hingedabove the projection aperture and connected with .the driving mechanismso as to close the aperture the moment rotation of the driving shaftceases. It sometimes happens however, particularly with previously used,worn, or spliced films, that the fil'm will remain stationary with thesame portion over the aperture long enough to be heated to theipoint" ofignition, althoughthe operatorfnay continue operating the mechanism inthe usualma-nner, thereby keeping thegfire shield ope .Th'e'objecfi-of." my pre utoihatically. on 1 normal length of time, to cutofl the light from the projection aperture and thereby prevent the filmbecoming heated to the point of ignition. I

In the embodiment of my invention illustrated in the accompanyingdrawings, and descrlbed in the following specification, I accomplishthis result by the provision of a novel stop mechanism ope-rated by avariat1on in the tension of the film between the upper continuouslyoperating sprocket and the intermittent sprocket to stop the entire-machine so the fire shield will close in the supplementary shieldwithout stopping the machine at all, and it is to be understood that myinvention is not limited to the construction here shown. So far asI amaware .I am the first to provide mechanism of any kind in a motionpicture machine-to eliminate the defects noted, and the appended claimsare to be construed broadly in accordance with the spirit of the law.

In the accompanying drawings, Figure 1 is a vertical section through thehead of a motion picture machine equipped with my improved stopmechanism. Fig. 2 is a plan view partly in section of a portion of themechanism shown'in Fig. 1. Fig. 3 is a view generally similar to Fig. 2but showing a sli ht modification. Fig. 4 is a sectional detai view ofthe mechanism shown in Fig. 3. Fig, 5 is a detail view of an automaticcircuit breaker that may be used either with or without the mechanicalstop mechanism. Fig. 6 is a sectional view of a slightly modified detailof the construction shown in Fig.

like characters indicate like parts throughoutthe several views, -1indicates theframe of the machine in which" is mounted as showndiagrammatically in Fig. 1 the. main 1 d'riving v shaft '2 Wl110l1 isconnected the foperating handle, not Q shownI Atached t0 the shaft" '2is the 1 main driving gear-i 3 from which is continuously: driven bysuitable intennediate .gears e are or up per'feed sprocket 4 for thefi1m 5. The'film1 passes downward and past the projection apertures 6 inthe frame, between the guide springs 7 and the rear wall 8 of the. headto the intermittently operated sprocket 9. This sprocket is operatedfrom the shaft 2 by means of suitable gearing lncludlng a Geneva orother intermittent movement 10 at a speed such that the length of filmnormally fed intermittently by the sprocket 9 is equal to the length fedcontinuously by the sprocket 4 in the same interval. Beneath thesprocket 9 a lower continuously drivensprocket 11 for feeding the filmto the take up. reel is provided, this sprocket being driven by'suitablegears 11 in synchronism with the sprocket 4 so that the film may bethreaded 1n the machine with suitable loops or slack between of the fireshield when the machine is stopped and when it is in motionrespectively. Any of the improved mechanisms now in use for this purposemay be employed with the stop mechanism I have illustrated, for instancethe centrifugal clutch 13 on the spindle of the shield driven from themain shaft 2. At 13 I have indicated an electric are as a conventionallight, which in practice is of course mounted in the usual lamp-housewith suitable condensers, etc.

The mechanism so far described constitutes essential elements of amotion ,picture machine of ordinary construction, and I will nowdescribe the construction and operation of my improved stop mechanism asapplied to it. The upper sprocket 4 is fast to a spindle 14 which isrotatably mounted in a bearing 15 in the frame 1 and-projects beyond thesame to receive the driving gear 4. A

gear 16 is attached to the spindle 14 adjacent the bearing 15 andloosely mounted on the shaft between the gear and the bearin is aratchetwheel 17. The ratchet wheel 1 is provided with a recess in itsface adjacent the gear wheel in which is seated a coil spring 18 havingone of its ends attached to the ratchet wheel, and its other endconnected to the spindle 14. Pivoted to the frame in position to engagethe ratchet wheel is a pawl 19 provided .with a spring 20 to hold thepawl normally out of engagement with the ratchet and also with arearward extension 21 lying under a pin 22 projecting from the side faceof an arm 23 which is rotatably mounted on the bearing 15 concentricwith the spindle 14. The end of the arm which carries the pin 22 isprovided with a Weight 23 and in the end of the arm on the opposite sideof the bearing there is rotatably mounted a spindle 24 having attachedto its end a gear 25 meshing with the gear 16. Projecting eccentricallyfrom the face of the gear'25 are two diametrically opposite pins.

synchronism with the intermittent action of v I the sprocket 9. It willbe noted that the sprocket 9 makes four intermittent movements to eachcomplete rotation and the sprocket 4 is the same diameter as thesprocket .9. Hence the gear 25 carrying the two pins 26and thereforeefi'ectlng two take up operations for each rotation, is driven at twicethe speed of the sprocket 4.

The operation of this form of the mechanism will now be described.Suppose the film being exhibited contains a defective splice asillustrated at 29 in Fig. 8. Such a splice if it holds togethersutliciently to be wound on the reel will usually pass the sprocket 4without separating, for the pull of this sprocket is uniform and theresistance offered by the film is slight. When however the splicereaches the projection aperture its double thickness beneath the springs7 offers such resistance that the sudden pull of the intermittent feednot infrequently causes the splice to part leaving the end of the filmin the path of the intense 1 light and heat of the lamp. The momenthowever the advanced endof the film stops, the loop in the film engagedby the pins 26 enlarges, thereby permitting the weight 23' to drop sothat the pin 22 engages the endof the pawl, for'c'ing'its tooth intoengagement with the ratchet wheel, stopping the rota; tion of theratchet wheel and opposing the resistance of the spring 18' to thefurther rotation of the spindle '13, thereby stopping the machinewithout shock or jar and allowing the fire shield to close in the usualmanner before the heat fromthe lamp can possibly ignite the film.

Another common defect in used filmslis the destruction of the sprocket loles in the margins of the film as indicated at 29* in Fig. 7. A-film'somutilated will have sufficient frictional engagement with the sprocket 4to be fed by it but will slip on the intermittent sprocket leaving-thefilm stationary at the projection aperture where it would shortly igniteif the stop mechanism did not operate as described to permit thefire-shield to close. a

In Figs. 3 and 4 I have shown a sli ht modification of the film engagingmec anism carried by the arm 23'. Instead of the pins 26 attached to theface of the gear I form the spindle 24 with a prolongation 24 and attachto it two cams 30 shaped to vary the path of the film in exact accordwith the intermittent movement of the film so that the arm 23 remainsstationary during the normal operation of the machine instead ofoscillating up and down as would be the case if the films engaged thespindle 24 directly. As the cams have but one take up action for eachrotation they are driven at four times the speed of the sprocket 4;.

In Fig. 5 I have illustrated a circuit breaker which may be employedwhen the projecting machine is driven by an electric cess in the face ofthe ratchet and held motor. Fast to the arm 23 is an insulated contactpiece 31 engaged when the arm is horizontal by a spring contact '32insulated from the machine by a block 34. The current for driving themotor passes through the contacts so that when the arm drops the circuitwill be broken and the motor stopped. This device may be used alone orin connection with the mechanical stop and it may also be used ifdesired to cut off the current to the lamp of the machine either aloneor in connection with the stop mechanism.

A further slight modification is illustrated in Fig. 6 in whichstructure the spring connection between the ratchet 17 and the spindle14 is dispensed with and in place thereof a frictional connection isprovided comprising a leather washer 35 seated in the reagainst the faceof the gear 16 by a disk spring 36 between the'gear and the ratchet.When the ratchet is stopped by the pawl in the manner described thewasher 35 acts as a brake on the gear and offers such resistance torotation that the operator cannot turn the machine fast enough for thecentrifugal clutch 13 to keep the shield open.

I have described two of the most common causes of failure of the feedmechanism but it will be understood that any accident or offilm betweenthem and forvarying dimensions of said loop,.' mea-ns for drivi'ng"defect which causes the film to remain an unusual time at the projectionaperture, such for instance as the'breaking of the pin of the Genevamovement, will ,cause ,the machine to stop and the fire shield to closebefore possibility of damage. I have. men-- tioned several ways in whichthe llght can be cut off without stopping the machine but I prefer tostop the entire machine as such stopping calls the operators attentionto the defect immediately before the exhibition has been long delayedand before the broken film has run off the sprocket so as to necessitatere-threading the machine.

Having thus described my invention, desire to secure by Letters What Iclaim and Patent is 2-- 1. In a motion picture projectinginagi chine,the combination=of successive film-- feeding devices "operated tomaintain a loo -.1neans for rendering saiddevices ,-'inopera---.t1've'fand s multaneously cutting off said devices inoperative, saidmeans having control mechanism comprising a film-engaging membernormally engaging said film in the loop thereof and operating upon anabnormal variance in the size of the loop to render said driving meansinoperative.

2. In a motion picture projecting machine, the combination of successivefilm feeding devices operated to maintain a loop of film between them,means for driving said devices, means for rendering one of said devicesinoperative, and means for controlling said last named means comprisinga filmengaging member positioned to be normally engaged by the film inthe loop thereof and operating upon an abnormal enlargement of the loopto render said driving means inoperative.

3. In a motion picture projecting machine, the combination of successivefilm feeding devices operated to maintain a loop of film between them,means for driving said devices, means for rendering one of said devicesinoperative, and means for controlling said last named means comprisinga film-engaging member positioned to be engaged by the film in the loopthereof and a connection between said film-engaging member and saidmeans to operate the latter upon movement of said connection, saidfilm-engaging member being constructed to maintain its engagement withsaid film during a limited variance in the size of said 11000p withoutmoving said connecting mem- 4. In a motion picture projecting machine,the combination of successive film feeding devices for feeding the filmacross a path of light, means controlled by said film feeding devicesfor cutting off said light, means for driving said film feeding devicesto maintain a loop of film between them, said driving means comprising amain driving shaft having geared driving connections with said filmfeeding deyices, means for rendering one, of said devices inoperativecomprising amembe'r, adapted to engage and stop one element of saidgeared driving connections, and meansjfor actuating said lastnamed'means comprising a member to be engagedby said loop of film and having amechanical connection with said last named member.

5. In a motion picture projecting machine, the combination of successivefilm feeding devices for feeding said film across the path of light,means for cuttingolf the light from-the film, means for driving said, Idevices to'maintaln a loop of -filnthetween them, said drivingmeanscomprising iazmain drivin g'fshaf-t' having geared driving con-.ne'c'tions with said film ,feeding fievices light, comprising .amemberadaptedjto en gage and stop one element of said geared my hand at thecity, county and State of driving connections, and means for contro1- New York, this 31st day of December, 1912. ling said last named meanscomprising a 7 film-engaging member having direct me- NICHOLAS POWER. 5chanical connection "With said last named Witnesses:

member. W. B. MORTON,

In Witness whereof I have hereunto set L. E. JOHNSTON.

